Apparatus for railway train communication systems



Nov. 12, 1940. w. P. PLACE 2,221,654

APPARATUS FOR RAILWAY TRAIN COMMUNICATION SYSTEMS Filed A ril 12, 1940 ZZ/z'l 11 71 RPlac'e; BY I H16 ATTORNEY Patented Nov. 12, 1940 Parse-r Q'FHCE APPARATUS FOR RAILWAY TRAIN COM- MUNICATION SYSTEMS Willard P. Place,.Wilkinsburg, Pal, assignor to The Union Switch & Signal Company, Swis iii vale, Pa., a corporation of Pennsylvania Application April'12, 1940, Serial No. 32$,321

, 17 Claims.

My invention relates to apparatus for railway train communication systems, and more particularly to apparatus for railway train communication systems which use the track rails as a part 5 of the transmitting circuit.

Railway train communication systems for'telephone communication between a station located on a vehicle of a train such as a locomotive of a freight train, and another station remote there:

10 from, such as a station located in the caboose of the freight train, are in use. Telephone current is applied to the track rails at the sending station either inductively through the medium of an inductor mounted for inductive relation with the rails or conductively through the medium of a circuit having contact with the rails. The current flows in the rails in both directions from the point at which it is applied thereto and returns through the ground and other conductors. At the receiving station current is received from the rails through the medium of a circuit element either inductively or conductively coupled with When the track railsare formed the track rails. into consecutive insulated track sections for either or both wayside and cab signal systems the insulated r'ail joints may interfere with the eiTective transmission of the train telephone current because such telephone current must at times flow from the rails of one track section to the rails of an adjoining track section.

Accordingly, a feature of my invention is the provision of novel and improved apparatus for conducting such communication current around the insulated rail joints which separate two track sections and wherewith interference to the operation of the usual wayside.v and cab signal systems is avoided. I

Another feature of my invention is the provision of novel and improved apparatus of the type herein contemplated wherewith the,- track rails of adjoining insulated sections are shunted and the insulated rail joints-separating thesections are by-passed in' such a manner'that noise in the telephone apparatus caused by current surges produced by the train wheels running on and ofi the insulated rail joints is substantially eliminated. v

The above features, as well as other advantages of apparatus embodying my invention, -I attain by providing low resistance by-passor shuntcircuits one around each insulated rail joint separating two track sections and each of which circuits is controlled by at least one of the track relays of the adjoining sectionsso that the by- 0 passed circuits are closed only while a train is passing from one section into the other. Each oftsuch, by-pass circuits is periodically interrupt-, ed so .that when a-train vacates the rear section of such adjoining sections the track rlay of such section isreenergized in the usual'manner during the first interval the by-pass circuits-are interrupted and hence theusual train signaling ,devices are restored to their normal condition with little orno-delay due to the by-pass circuits; Furthermore, I preferably provide an auxiliary relay having the heels of four contact fingers connected together and their front contacts one connected to each of the four rails of the two'adjoining sections. Thus the four rail" ends of'the'two adjoining track sections are connected'to a common point thereby short circuiting the rails of each section and by-passing the insulated rail joint when the auxiliary relay is pickedup. This'auxiliary relay is controlled by the track relays of the assooiatedtrack sections and'also' by a contactofi'a coding device such as the codeltransmitter of one of the sectionswhen' coded current is supplied. at times to the'track circuit for control'of either or both wayside and cab signals. v

I shall describe two forms of apparatus em boidying my invention, and shall then point out the novel features thereof in claims.-

In the accompanying drawing Figs. 1 and 2. are diagrammatic views showing two diiierent forms of apparatus each of which embodies my invention when used with track sections having track circuits supplied normally with non-coded alternating current for control of wayside signals and which track circuits are supplied with coded 35 alternating current when a train occupies an as-' sociated section for control of cab signals. In each of the two views like reference characters designate similar parts. 1

It will be understood that my invention is not limited to this one arrangement of track circuits for insulated track' sections, but serves to illustrate the general application of apparatus embodying my invention. 1 7

Referring to Fig. 1, the reference character's la and lb designate the track rails of a stretch of railway over which traffi-c normallymoves in the direction indicated by an arrow and which rails are formed by the usual insulated rail joints 2 into consecutive track sections of which sections 5 only the one section AB and the adjacent ends of the two adjoining sections are shown for'the sake of simplicity, since these are suflicient for a full understanding of my invention. E ach track section is provided with a track circuit for con- 55 trolling both wayside and cab signals and each of which track circuits comprises a source of current connected across the rails at one end of the section and a track relay connected across the rails at the other end of the section. The type of track circuit is immaterial, and may be any one of the well-known forms in present day use. The track circuits would be preferably alike and a description of the track circuit for section AB will serve for an understanding of all. As shown in Fig. 1, the track circuit of section AB is normally supplied with non-coded alternating current of the frequency of 60 cycles per second for the control of an alternating current track relay which governs a wayside signal. The track circuit is supplied with alternating current of the frequency of cycles per second coded at a predetermined code rate for controlof a cab signal when a train occupies the section, such coded alternating current being in accordance with traffic conditions in advance of the section. The immediate source of current for the track circuit of section AB is a track transformer Ti whose secondary winding 3 is connected across the rails adjacent the exit end of section AB over wires 4 and 5 witha current limiting reactor 6 interposed in wire 5. The primary winding .1 of track transformer TI is normally supplied, that is, when section AB is unoccupied, with 60 cycle alternating current from the secondary Winding 8 of a line transformer T2 whose primary winding 9 is connected with a generator, not shown, adaptable of supplying alternating current of the frequency of 60 cycles persecond. To be explicit, the secondary winding 8 of transformer T2 is connected across two bus terminals BX and 0X andprimary winding 1 of track transformer TI is connected across the bus terminals BX and CX by a circuit which can be traced from terminal BX over wire l5, back contact l6 of a relay VB to be later referred to, wire I], primary winding 1 of transformer TI and wire I 8 to terminal CX.

When the track section AB is occupied, the primary winding 1 of track transformer TI is disconnected from the 60 cycle source of current in a manner to later appear and is connected with the secondary winding ID of another line transformer T3 whose primary winding l l is connected with a generator, not shown, adaptable of supplying alternating current at the frequency of 100 cycles per second, such 100 cycle alternating current being coded at a predetermined code rate, as will presently appear.

A track relay ATR responsive to 60 cycle alternating current is connected across the rails adjacent the entrance end of section A-B over wires l2 and I3. Hence track relay ATR. is normally energized to control a wayside signal for governing traflicthrough section AB. Such wayside signal is not shown since it forms no part of my invention and may be anyone of the several well-known types of wayside signals. Track relay ATR when energized and picked up opens a back contact 14 interposed in a linecircuit for an approach control relay VB as will be readily understood by' an inspection of Fig. 1. When a train enters section AB to shunt the track relay ATR, this relay is released to close back contact l4 whereupon approach control relay VB is energized and picked up to open back contact [6 and close front contacts I9, 20 and 2|. The opening of back contact 16 removes the normal supply of 60 cycle alternating current from primary Winding 1 of track transformer Tl. The closing of front contact l9 completes a simple circuit easily traced for the motor winding 22 of a code transmitter CT and code transmitter CT is operated.

The code transmitter CT may be of any one of several types well-known in the art and is here shown as being of the motor type. When motor winding 22 of code transmitter CT is energized a shaft indicated by a dotted line 23 is rotated at a predetermined rate of, say, for example, 15 revolutions per minute. A cam 24 is mounted in-fixed relation on shaft 23 and rotates at 15 revolutions per minute, cam 23 being preferably of suitable insulating material. The cam 24 is constructed with 8 teeth and has associated therewith a code contact member 26, the arrangement being such that contact member 25 is biased by any convenient means to engage the outer surface of cam 24 so as to be actuated by each tooth of the cam. A contact |25-l25a is closed when contact member 26 is actuated by a tooth of cam 24 and a contact |20|2fib is closed when contact member 26 is in the space between two teeth of the cam. It follows that contacts i2U--l20a andl20-l2i3b are periodically opened and closed at the code rate of times (15x8) per minute as long as motor winding 22 of code transmitter CT is energized.

A'second shaft indicated by a dotted line 23a is operatively connected with shaft 23 through a gear train indicated conventionally at 21, and a cam-25 of suitable insulated material is fixed on shaft 23a, the arrangement being such that shaft 23a and cam 25 are rotated at a rate of, say, 4 revolutions per minute as long as the code transmitter CT is operated. Cam 25 is provided with a depressed portion 28 and has associated therewith a contact member 29, which member is biased to engage the outer surface of the cam with the result that a contact 3fl-3l is operated by contact member 29, the contact 3U3l being normally closed and opened when the contactmember 29 engages the depressed portion 28. The depressed portion 28 of cam 25 is proportioned so that the interval it is adjacent contact member 29 and contact 30-3l is open is of the order of one second or somewhat greater than the cycle interval of the code rate efiected by cam 24.

It is to be understood, of course, that my invention is not limited to the specific code rates here specified for the contact member 26 operated by cam 24 or to the specific period the contact 3B3l operated by cam 25 is open and these intervals are given by way of illustration as an aid to a clearer understanding of my invention. v The contact l20-l2ila is interposed in a circuit which connects secondary winding H] of transformer T3 with primary winding 1 of track transformer TI, the circuit comprising right hand terminal of secondary winding it, front contact 20 of relay VB when that relay is Picked up in the manner explained hereinbefore, contact I2i]l20a, wire i1, primary winding 1, wire l8 to bus terminal GK and thence to the lefthand terminal of secondary winding l0. Consequently, when a train enters section AB to shunt relay ATR. and pick up approach control relay VB, which in turn causes code transmitter CT to be active and disconnects the normal source of 60 cycle alternating current, alternating current of 100 cycles per second coded at the rate of 120 interruptions per minute is supplied to the track circuit of section AB. It is to be understood, of course, that this coded current is in actual practice also governed by traflic conditions in advance of section AB byany or; the well-known means but which control isiio't shown for the sake of simplicity since it form-ch0 part of my invention. I i I The contact l20--l2llb is interposed in-asceond circuit over which the primary winding 1 of track transformer TI is connected'across the bus terminals BXand CX for supplying alternating current of 60 cycles per secon'd'to the track cir cuit. This second circuit extends from terminal BX, over wire l5, aback con'tact32 of a track'relay BTR for the track 'circuit' ofthe Section next in 1 advance of section A'- -B, contact l20-l20b, wire l1, primary winding 1 and wire l8 to terminal CX. I

From the foregoing description of the track circuit of section A --B it is to-be seen that nor mally non-coded alternating current of-6 0 cycles per second is. supplied tothe track circuit for energizing track relay ATE; when a trairi'enters section AB to shunt relay ATR the approach control relay VB is picked up to disconnect the 6-0 cycle source and to cause coded 100 cycle current to be supplied to the track circuit; when the train moves into the section next in advance of the section AB to shunt track relay BTR 60 cycle alternating current is appliedto the track circuit of section AB during each ofi period of the coded 100 cycle current and when the train vacates section AB track relay'ATR is reener-' gized with" the result that app-roach control relay VB is released to discontinue operation of code transmitter CT and cause non-coded current to be supplied to the track'circuit of section A-B,

The apparatus of track circuit of section A -B thus far described is that in general use except cam of the code transmitter CT and the parts associated with cam 25. v p

I shall now describe the apparatus embodyin my invention asit is applied to the track circuit of section AB; An auxiliary'relayAB of the type responsive to 60 cycle alternating current is controlled over a circuit including terminal BX, wire l5, front contact 2l of approach control relay VB, backc'ontact" 33 of track relay BTR, c0ntact3U-3l of code transmitter CT, wire 34, winding of relay and to terminal CX'. Hence when approach control relay -VB- has been picked'up' in response to a train occupying section AB and the head end of the train moves into the section next in advance to shunt track relay BTR, the auxiliary relay AB is picked up except for the interval the depressed portion 23 of carn 25"isadjacent contact member29 and contact 30-'3l is open. -In other words when a train occupies both section A B and the section next" in advance the auxiliary relay AB is picked up except for recurrent intervals during each of which intervals relay AB: is released. Furthermore, it'is to be noted that the intervals at which the auxiliary relay AB is released are relatively-far apart and each-interval is somewhat greater than the cycle interval of the coded current supplied to the track circuit of section AB. Also when the track relay ATR. is re'ene'rgized to cause appr'oach controlrelayVB to'be releasedcpening front contact 2| the auxiliary relay AB isdeenerg-iz'ed" and released.

Auxiliary relay AB is provided withfour contact fingers 35, 36, 31 and '38. The so-called heels of these contact fingers areall joined" to a conductor 39. The front contact 40 of contact finger 35 is connected over wire: 41 to rail lw to the right of r the insulated rail joint'2 inter-- posed in rail la to electrically separate rail la of section AB from; the corresponding rail of the section next inadvance. In like manner the front contact 42 of contact finger 36 is connected over wire 43 with rail lb to the right of the insulated rail joint 2 interposed in rail lb between section AB and the section next in advance. The front contact 44 of contact finger 31 is connected over wire 45'with rail lb to the left of the insulated rail joint 2 interposed in that rail and front contact 46 of contact finger 38 is connected over wire 41 with rail la to the left cfthe insulated rail joint 2 interposed in that rail.- Itis to be seen, therefore, that when relay AB -is picked up closing front contacts 40, 42, 44 and 4 6, the rails la and lb of section AB are shunted over a circuit involving wire 41 connected to rail la, front contact 46, contact finger 33, conductor 39, contact finger 31, front contact 44 and wire 45 to rail' lb. Also the rails la,

and lb;of thesection next in advance are shunt ed over wire 4! connected to rail l a, front contact 40, contact finger 35, conductor 39, contact iinger' 36, front contact 42, and wire 43 to rail At the same time a low resistance circuitshunts the insulated rail joint 2 of rail Id at location B, the circuit including wire 4| connected to the rail to theright of the insulated rail joint, frontcontact 40, contact finger '35, conductor 39, contact finger 38, front contact 46 and-wire 41 to rail to the left 0f the insulated joint.

In like fashion a low resistance by- 'aass'circuit bridgesthe insulated rail joint 2 interposed in rail l-b atlocation B, the circuit including wire 43 connected to the rail to the right of the insulated rail joint, front Contact 42, contact finger 36, conductor 39jcontact finger 31, front contact 44 and wire' 45 to rail lb to the left of the insulated rail joint. It follows that when a train spans the insulated rail joints at location l3 to occupy both section- A'-'-'-B and the section next in advance and-auxiliary relay AB is picked up, each" insulated rail joint 2 at location B is bypassed lc'y' a low impedance circuitand an'y communica'tion current applied to the rails at some point along the section next in advance of sec-'1 tionA- -B win new to the ,rails of section AB with substantiallynoimpedanceat the insulatedraii joints at iocation' Bi Also "communication current appliedto the rails ;at any point along section AB flows to the rails of the section next in advance with substantially no interferenceat the insulated rail joints at lo'catiio'n B. Since theends of all four of the rails at location B are connected to a COmIIlOn' point (conductor 39') thernoving of the train wheei oh' and off'the' insulated rail joints will not materially vary the now of the communication current and noise in the telephone receiving apparatus due to surging of the telephone current is substantially" eliminated.

When the rear of the" train vacate's section A 'B, the. shuntor Icy-pass circuits controlled by relay, AB do 'not materially interfere with: the reenergizin'g of the-track relayATR; since: the first timeithe contact'3ll3l' of code transmitter CT is opened the auxiliary relay AB is released with the result that the 60 cycle alternating' current applied: to thetrackcircuitof sec-1 l 20--,l 20b of the code transmitter is effective to reen'er'gize the track'- relay :ATR' causing the japproach control relay tion A B over: contact V3 to be; released, aiter which the auxiliary relay AB remains ld'eenergized and the by pass; or

' interval contact member 50 shunt circuits controlled thereby are open. -I have found that such by-pass circuits around a pair of insulated-rail joints may be periodically opened in the manner effected by the code transmitter contact 30 3l without materially interfering with .the transmitting of the telephone current.

Referring to Fig. 2, the track rails la and lb are formed by insulated rail joint 2 with a track section AB provided with a track circuit the same as in Fig. 1 and the description thereof will not be repeated. In Fig.2, low resistance bypass circuits around the insulated rail joints separating section AB from the section next in advance are completed by contacts operated by the code transmitter CT and auxiliary relay AB is omitted. Looking at Fig. 2, the code transmitter CT is provided with a second cam fixed on shaft 23a the same as cam 25, the cam 50 being constructed similar to cam 25 and formed with a depressed portion 5| substantially like the depressed portion 28'of cam 25. Cam 50 isassociated with a contact member 52 for operating acontact 53-54 and which contact 53-54 is normally closed and is opened only during the is adjacent the depressed portion 5l.

A shunt or by-pass circuit-around insulated rail joint- 2 in rail l a at location B can be traced from rail la of section AB over wire 55, front contact 56 of approach control relay VB, contact 30-3l of code transmitter CT, back contact -330i track relay B'I'R and wire 51 to rail la "of -the section next in advance. A similar shunt or bypass circuit around the insulated rail joint 2 of rail lb can be traced from rail lb to the left of the insulated rail joint over wire 59, front contact 60 of approach control relay VB, contact 53-54 of code transmitter CT, backcontact 6| of track relay B'I'R and wire 62 to rail lb to the right of the insulated rail joint.

Hence when a'train occupies both section AB and the section'next in advance, to shunt both relays ATR and BTR, the by-pass circuits around the insulated rail joints 2 at location B are closed and telephone current applied to the rails of either section is transmitted to the rails of the other section with substantially no impedance at the insulated rail joints at location B. When the rear of a train vacates section AB of Fig. 2, the by-pass circuits are opened periodically by the contacts 30--3l and 53-54 of the code transmitter so that the 60 cycle alternating current applied to the track circuit of section AB over contact l20-l20b of the code transmitter is efiective to reenergize the track relay ATR and restore the apparatus associated with that track circuit to its normal position. In Fig. 2 the rails of the two sections are not shunted as is the case of Fig. 1.

Although I have herein shown and described only two forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spiritand scope'of my invention.

Having thus thus described my invention, what I claim is:

1. In apparatus for use with a system providing communication between a station located on a vehicle of a railway train and a remote station over a transmitting circuit including the track rails when the track rails are formed into consecutive insulated track sections each of which is provided with a track circuit supplied with a ainst current for energizing a track relay," the combination comprising a coding "device for a given track section operative at times to recurrently open a. normally closed contact, and circuit means including saidcontact of said coding device and a contact governed by the track relay for the track circuit of saidgiven section as well, as a contact governed by the track relay for the track circuit of the track section next in advance of said given section to shunt the insulated rail joints which separate said given section from said section next in advance. 1

2. In apparatus for USEIWith'a system providing communication between a station located on a vehicle of a railway train and a remote station over a transmitting circuit including the track rails when the track rails are formed into consecutive insulated track sections each of which is provided with a. track circuit supplied with current for energizing a track'relay, the combination comprising, a coding device for a given track section having a contact'which is periodically opened and "closed, a first normally open contact which becomes closed when a train occupies said given section, a second normally open contact which becomes closed-whena train occupies the section next in advance of said given section, and circuit means including said contact of said coding device, and said-first and second normally open contacts and connected with the track rails to bridge around the insulated rail joints separating said given section and said section next in advance.

3. In apparatus for use with a system providing communication between a station located on a vehicle of a railway train and a remote station over a transmitting circuit including the track rails when the track rails are formed into consecutive insulated track sections each of which is provided with a track circuit supplied with current for energizing a track relay, the combination'comprising, a coding device for a given track section operative to open-a normally closed contactat recurrent-intervals, and circuit means including said contactof said coding device and a back contact of. the track relay for the track circuit of the track section next in advance of said given section to form by-pass circuits around each of the insulated rail joints separating said given section and said section next in advance.

- 4. In apparatus for use with a system providing communication between a station located on a vehicle of a railway train and a remote station over a transmitting circuit including the track rails when the track rails are formed into consecutive insulated track sections each of which is provided with a track circuit supplied with current for energizing a track relay, the combination comprising'by-Dass circuit means connected to each rail on each side of the insulated rail joints separating a given track section and the sectionnextin advance of said given section to provide when closed low impedance paths around such insulated rail joints, a code transmitter for said given track section operated at times to periodically open and close a contact, and said code transmitter contact interposed in said bypass circuit means.

5. In apparatus for use with a system providing communication between a station located on a vehicle of a railway trainand a remote station over a transmitting circuit including the track rails when the track rails are formed into consecutive insulated track sections each of which is provided with a track circuit supplied with current for energizing a track relay, the combination comprising, an approach control relay governed by the track relay of a given track section to a first position when said given section is unoccupied and to a second position when said given section is occupied, a code transmitter effective when energized to periodically open and close a contact, a circuit including a second position contact of said control relay to energize said code transmitter, and circuit means in clud ing a second position contact of said control relay and said code transmitter contact and having connections to the rails at each side of the in sulated rail jointsseparating said given section and the section next in advance of said given sec tion to form low impedance paths around suchins lat d r l J n s f a 6, In apparatus ior use with a system providing communication between a station located on a vehicle f a a y t ai an a'rem 'e Station er-a transm t in circuit n di h track. rails when the tracl; rails are formed into consecut ve insu a ed trac e i s a h of which s r vid d i h a rack cir u t' p i s 'w rent for energizing a track relay, the'conibination comprising, an approach control relay governed by the traclg relay of a given track section to a first e iti n when sa d giver! e ii ufiocr cupied and to a second position when saidgiven section is occupied, code transmittenefi c'tive when energised to periodically open" and close a first and a second contact in stepwith eachother, a oircuit including a second position contact of said control relay to energize said code transmitter; a first by-pass circuit including a'second position contact of said control relay, aback contact'of the track relay for the track section next advance of said given section and said first code transmitter contactand connected to each side of thein sulate d' rail joint separating one of the track rails of said g iven'section and the corresponding rail of said section next in advance; and a second by-pass circuit including a second position fco'ntactiof said control relay, a hack contact of the track relay for said section next in advance and said second code transmitter contact and connected to [each side'of the insulated rail joint separating the other track rail of said given" section and the corresponding rail of said section next in advance.

'7. In apparatus for use'with a system providing communication between astation located on a vehicle of'arailway train and a remote station over a transmitting circuit including the track rails when the track rails are-formed into consecutive insulated track sections each of which is provided with a track circuit supplied with current for energizing-a track relay, the combination comprising, an approach control relay governed by the track relay of a given .tracksection to a first position when said given sectionis unoccupied and .to a second position when said given section is occupied, a first byl-pass circuit including a second position contact of said con,-

--trol relay and a back contact of the track relay for the track section next in advance of said given section connected to one of the track rails to each side of the insulated rail joint interposed in saidone track rail to separate said given sect n and sai ec x i ad ancaend a sec nd l ves circu t n din a SfiQQPd ms i e n act o sa d c ntr relay an a b k Famed of the track relay for said section next inadvance connected to the other track rail to each side Q the-insul d ra J int ini 1 edin id other track rail to separate said given section and said section next in advance.

' 8. In apparatus for use with a system providing communication between a station located'on a vehicle of a railway train and a remote station over a transmitting circuit including the track rails when the track rails are formed intofcon secutiveinsulated track sections each of which is provided with a track circuit supplied with current, for energizing a track relay; the combination comprising, an approach control relay governed by the track relay of a given track section to a first position when said given section is unoccupied and to a second position when said given section'is occupied, a first Icy-pass circuit including a second position contact of said'control relay and a hack contact of the track relay 1 for the track section next in'advance of said given section connected to one of the track rails to each'side of the insulated rail joint interposed in said one track rail'to separate said given section and said section next in advance, a second lay-pass circuit including a second position contact of said controlrela'y and a back contactof the track relay for said section next in advance. r

connected to the other track rail to each side of V th'e'insulated rail joint interposed in said other track rail to separate said given section and said section next in advance, and means'for periodically opening each of said by-pass circuits.

9.'In apparatus for use with a system providing communication between a station located on a vehicle of a railway train and a remote station over a transmitting circuit. including thetrack rails when the track rails are formed into con fsecutive insulated track sections each of which is provided with "a track' circuit supplied with cur rent for energizing a trackrelay; the combination comprising, a coding device for a given track section effective when energized to periodically openand cl'ose'a contact, an'auxiliary relayfor saidgiven section, means including a contact of the track'relay of said given section for energizing said coding device, an energizing ,circuitin- .cluding said contact of the coding device and a contact of thetrack relayfor the section next in advance of said given section to energize said auxiliary relay, arid two Joy-pass circuits one for shunting around each of the insulated rail joints separating said given section andsaid section next in advance and each of" vwhich by-p ass circuits 11 9 149 9 fr m" cc a i said w e r y- 19-111 a pa atus .iar u e w t asystem P :ing communication between a station located on a vehicle of a railway train and a remote station over a transmitting circuit including the track when the track rails are formed into consecutive insulated track sections leach of which is provided with a track circuitsupplied with current for energizing a .track' relay," the cornhination comprising, an 'auxiliary relay for a given track section, a'first by a s iwu t includ n a im Contact of s iliary relay connected .to one of the track rails at each side or the insulated rail'joint interposed in an eeea t er ia e s f eir c semen n the section next inadvance, a second lay-pass cirsaid auxiliary relay, and other means for periodically rendering said energizing circuit means inefiective to energize said auxiliary relay.

11. In apparatus for use with a system providing communication between a station located on a vehicle of a railway train and a remote station over a transmitting circuit including the track rails when the track rails are formed into consecutive insulated track sections each of which is provided with a track circuit supplied with current for energizing a track relay, the combination comprising, an approach control relay and an auxiliary relay for a given track section, circuit means controlled by traflic conditions of said given section to operate said approach control relay to a first position or a second position according as said given section is unoccupied or occupied, an energizing circuit including a second position contact of said control relay and a back contact of the track relay for the section next in advance of said given section to energize said auxiliary relay, by-pass circuit meansincluding a front contact of said auxiliary relay connected to eachtrack rail to each side of the insulated rail joints separating said given section and said section next in advance, and coding means controlled over a second position contact of said control relay operative to periodically interrupt said energizing circuit.

12. In apparatus for use with a system providing communication between a station located on a vehicle of a railway train and a remote station over a transmitting circuit including the track i rails when the track rails are formed into consecutive insulated track sections each of which is provided with a track circuit supplied with current for energizing a track relay, the combination comprising, an auxiliary relay for a given track section and which relay is provided with four contact fingers having their heels all connected together by a single conductor, a first circuit including the front contact of a first and a second of said contact fingers connected across the rails of said given section, a second circuit including the front contact of a third and a fourth of said contact fingers connected across the rails of the section next in advance of said given section, said first and second circuits together with said single conductor forming-a bypass circuit around each insulated rail joint separating said given section and said section next in advance When said auxiliary relay is picked up, 'an energizing circuit controlled over a bank-contact of the track relay for said given section and a back contact of the track relay for said section next in advance to pickup said auxiliary relay, and a coding device having a contact interposed in said energizing circuit to cause said auxiliary relay. to be periodically released.

13. In apparatus for use with a system providingcommunication between a station located on a vehicle of a railway train and a remote station over a transmitting circuit including the track rails when the track rails are formed into consecutive insulated track sections each of which is provided with a track circuit supplied with current for energizing a track relay, the combination comprising, an auxiliary relay for a given track section and which relay is provided with four contact fingers having their heels. connected together to 'form a common terminal, front contacts of a first and a second of said four contact fingers connected across the rails of said given section and front contacts of a third and a fourth ofsaid contact fingers connected across the railsof the section next in advance of said givensection to provide shunt paths around the insulated rail joints separating said given section from said section next in advance, and an energizing circuit including a first contact responsive to traffic conditions of said given section and a second contact responsive to traffic conditions of said section next in advance to energize said auxiliary relay.

14. In apparatus for use with a system providing communication between a station located on a vehicle of a railway train and a remote station over a transmitting circuit including the track rails when the track rails are formed into consecutive insulated track sections and each of which is equipped with a track circuit supplied with current from one source to energize a track relay when the section is unoccupied andwith current from another source coded over a code transmitter contact operated at a predetermined coderate when the section is occupied, the combination comprising, another contact operatively mounted on the code transmitter of a given track section to be closed except for recurrent inter vals each of which intervals'is greater thanthe cycle interval of-said code rate, and circuit means including said other contact to bridge'around the insulatedrail joints separating said given section and the section adjacent thereto.

15. In apparatus for use with a system providing communication between a stationlocated on a vehicle of a railway train and a remote station over a transmitting circuit including the track rails when the track rails are formed into consecutive insulated track sections and each of which is equipped with a track circuit supplied with current'from one source to energize a track relay when the section is unoccupied and with current from another source coded over a code transmitter contact operated at a predetermined code rate when the section is occupied, the combination comprising, another contact operatively mounted onthe code transmitter of a given track section to be closed except for recurrent intervals each' of which intervals is slightly greater than the cycle interval of said code rate, and circuit. means including said other contact and a back contact of the track relay for the section next in advance of said given section to by-pass the insulated rail joints separating said given section and said section nextin advance.

16, In apparatus for use witha system providing communication between a station located on a vehicle of a railway train and a'remote station over a transmitting circuit including the track rails when the track rails are formed into consecutive insulated track sections each of which 'is provided with a track circuit supplied with'currentfor energizing a track relay, the

combination comprising, anjapproach control section next inadvance, and asecond by-pas s circuit controlled over a second,positioncontact of saidapproach control relay and aback eontact of the track relay for said section next in advance and connected to the other track rail to each side of the insulatedrail joint interposed in said other track rail to separate said given section and said section next in advance.

17. In apparatus for use with a system providing communication between a station located on a vehicle of a railway train and a remote station over a transmitting circuit including the track rails when the track rails are formed into consecutive insulated track sections each of which is provided with a track circuit supplied with current for energizing a track relay, the combination comprising, an approach control relay governed by the track relay of a given track section to a first position when said given section is unoccupied and to a second position when said given section is occupied, and two by-pass circuits one connected around each of the two insulated rail joints interposed one in each track rail to separate said given track section from the section next in advance and each of which by-pass circuits is controlled by a second position contact of said approach control relay and a back contact of the track relay for said section next in advance.

WILLARD P. PLACE. 

